The invention relates to a steam iron having a water storage tank, an evaporation chamber to provide steam for ironing, and a drip valve for regulating the flow of water from the tank into the evaporation chamber.
Steam irons of this type have long been known. They may be used either as dry irons or as steam irons, as desired. For steam ironing, a metered quantity of water is fed from the tank into the evaporation chamber provided in the soleplate of the iron via the drip valve. As the hydrostatic pressure of the column of water in the water storage tank bearing on the valve is reduced, the quantity of steam produced in the evaporation chamber and escaping through the soleplate falls sharply over a certain period of time. In addition, during the steam ironing operation, pressure is built up in the evaporation chamber which affects the quantity of water flowing out of the drip valve. In order to equalize the pressure different in the chamber and in the interior of the tank, it has been proposed that the tank and the evaporation chamber be connected to each other by a pressure equalization tube (DE-AS 19 31 847). With this type of pressure equalization, steam flows out of the evaporation chamber through the pressure equalization tube into the upper part of the water storage tank during steam ironing. The steam is at a temperature of about 100.degree. Celsius. Consequently, the upper part of the steam iron, particularly the handle, is heated to such an extent that the handling of the steam iron is greatly affected and the number of materials from which the handle can be manufactured is reduced considerably.
In order for the pressure equalization to operate satisfactorily, the tank in known steam irons must be tightly sealed during steam ironing so as to prevent pressure equalization with the atmosphere. A leaky sealing mechanism or a fill opening which is not quite closed will cancel out the effect of pressure equalization entirely.